The present invention is generally related to vehicles and more particularly related to a vehicle for use on a wide range of terrain, including uneven and/or steep terrain having a variety of soil conditions. The vehicle of the present invention offers many advantages over conventional vehicles and can replace conventional vehicles in performing a variety of tasks.
Most conventional vehicles such as agricultural tractors, front end loaders and bulldozers are either driven by four wheels or by a pair of laterally spaced, parallel tracks. Four-wheeled vehicles have a pair of laterally spaced front wheels and a pair of laterally spaced rear wheels that engage the ground and rotate during vehicle movement. Typically, one or both pairs of wheels are driven to move the vehicle. The wheels of the wheel-driven vehicles are generally large and have treat designs tread aid in moving the vehicle over sand, clay and mud. Although capable of moving over terrain having a variety of soil conditions, conventional wheel-driven vehicles frequently become stuck because all of the tractional forces and driving surfaces of the wheels are not always put to the ground. Typical track-driven vehicles employ steel or rubber endless tracks that are driven to move the vehicle over the ground.
Conventional four wheel vehicles and conventional two track vehicles often cause environmental damage when used in natural areas. Recently, environmental concerns have been raised about the disruption of the topsoil which occurs when conventional loader/bulldozer-type vehicles are operated on the topsoil, sand or other soft terrain of sensitive natural areas. For example, in the tree harvesting industry, construction industry and/or the agricultural industry, the operation of conventional vehicles of the type described may cause significant damage to the topsoil, which in turn may result in the formation of ruts which may lead to soil erosion.
It is self evident from the above that the advantage of a two-track tractor vehicle over a four-wheeled tractor vehicle is its traction and stability. On the other hand, the advantage of a four-wheeled tractor vehicle over a two-track vehicle is in its ease of handling and maneuverability.
To a considerable extent, the tractor vehicle of my U.S. Pat. No. 5,615,748 patent achieves the advantages of both two track and four wheeled tractor vehicles. This is because it provides a central track for traction and stability and two outrigger wheels for ease of handling and maneuverability.
The outrigger wheels of my ""748 tractor vehicle were steerable about a generally upright steering axis. The wheels were controlled using a steering mechanism capable of turning both wheels generally in unison about their respective steering axes to effect turning movement.
In my U.S. Pat. No. 6,044,921, it is disclosed that enhanced ease of handling and maneuverability can be achieved by utilizing outrigger wheels which are steered by changing the relative driving speed between the two outrigger wheels rather than by moving them in unison about upright steering axes. Further enhancement can be obtained by mounting the outrigger wheels for vertical movement and utilizing hydraulic cylinders and a control system therefor to maintain the wheels in ground contact.
The ""748 or the ""921 tractor vehicle, enhanced as aforesaid because it includes a central track and two outrigger wheels, is uniquely set up to enable a substantial portion of the load support to be shifted between the central track and the outrigger wheels. For example, if the hydraulic cylinders which keep the outrigger wheels in ground contact are adjusted so that a substantially low-pressure condition exists, the central track will support most of the vehicle load on the ground. As the pressure conditions in the hydraulic cylinders are increased, more and more of the vehicle load will be assumed by the outrigger wheels.
This substantial shift in load support occurs without any shifting of the load itself or any tilting of the frame. In contrast, the only way load support can be shifted between the two tracks of a two-track tractor or the four wheels of a four-wheel tractor is to shift the load itself. This unique load support shifting capability made possible by the use of hydraulic cylinders to keep the independently driving outrigger wheels on opposite sides of the central track in ground contact, enables traction and stability to be enhanced while at the same time further enhancing the ease of handling and maneuverability of the tractor vehicle.
Since existing two track tractors and four wheeled tractors do not have this load shifting capability, once they become stuck or bogged down in sloppy ground, there is nothing that can be done by the tractor itself to extricate itself from its mired condition. Shifting of the load carried between the central track and the outrigger wheels of the present vehicle allows the vehicle itself to vary the mired condition sufficiently to extricate itself from any one mired condition.
There is a need to make improvements in the functions of the disclosed vehicle or the way in which existing functions are achieved in order to make the vehicle more cost effective and otherwise more acceptable to a user.
It is an object of the present invention to make such improvements and hence fulfill the need expressed above. In accordance with the principles of the present invention, this objective is obtained by providing a vehicle having improvements in combination with other vehicle components which comprise a frame assembly and an engine assembly carried by the frame assembly constructed and arranged to generate power. A drive track assembly is provided on the frame assembly which includes a series of rollers including a drive roller and an endless track trained about the rollers so as to provide an operative ground engaging flight extending longitudinally with respect to the frame assembly. A power operated track mover is operatively connected to the drive roller to move the operative flight in ground engaging relation and a pair of left and right driving and steering wheels are disposed on opposite sides of the drive track assembly in flanking relation thereto.
Each of the wheels has (1) mounting structure supporting the wheel for rotational movement about a rotational axis mounted on the frame assembly for vertical movement between extended and retracted positions with respect thereto; (2) a power operated wheel rotator connected thereto to rotate the associated wheel about its rotational axis; and (3) a power operated vertical mover constructed and arranged to move the mounting structure with respect to the frame assembly between the extended and retracted positions thereof.
The arrangement of the wheel mounting structures and vertical movers with respect to the frame assembly and track frame structure is such that movement of the wheel mounting structures by the vertical movers with respect to the frame assembly between the extended position thereof creates a shift of load between the wheels and the track assembly progressively between a maximum traction condition wherein the load is shared relatively less by the wheels and by the entire operative flight of the track and a maximum turning tricycle condition wherein the load is shared relatively more by the wheels and by only a portion of the operative flight of the track with the remainder of the operative flight of the track held out of ground contact.
An electronic controller is provided which is operable to control (a) an amount of power supplied from the engine assembly to the power operated track mover; (b) an amount of power supplied from the engine assembly to a left one of the wheel rotators; (c) an amount of power supplied from the engine assembly to a right one of the wheel rotators; (d) an amount of power supplied from the engine assembly to a left one of the vertical movers and (e) an amount of power supplied from the engine assembly to a right one of the vertical movers. A speed input system is communicated to the controller. The speed input system is operable to transmit a speed signal to the controller indicative of a selected speed at which the vehicle is to be moved. The controller is operable to receive the speed signal and responsively control the amount of power supplied from the engine assembly to the track mover and the wheel rotators so as to move said vehicle at the selected speed.
A steering input device is also communicated with the controller. The steering input device is operable to transmit straight and turning signals to the controller indicative of a selected straight vehicle movement and of a selected angle at which the vehicle is to be turned. The controller is operable to process the steering signals transmitted thereto and responsively control (a) the respective amounts of power supplied from the engine assembly to the track mover the wheel rotators and the vertical movers such that (1) when a straight signal is processed, both wheels rotate at the same speed in uncoordinated relationship with the track speed and the wheel mounting structures are in relative retracted positions with respect to the frame assembly presenting traction condition wherein the load is shared between the wheels and the entire operative flight of the track assembly, and (2) when a turning signal is processed an outer wheel with respect to the selected angle of turn rotates at a greater speed than an inner wheel with respect to the selected angle of turn to thereby effect the selected turn and the wheel mounting structures are in relative extended positions relative to said frame assembly presenting a turning tricycle condition wherein the load is shared between said wheels and only a portion of the operative flight of the track.
In accordance with the principles of the present invention, the improvements which are combined with the aforesaid vehicle components include one or more of the following three improvements: (1) The controller has connected therewith a controlled lateral tilt input system operable to generate a lateral tilt signal indicative of a sustained vehicle movement along a slope in a direction wherein a downhill wheel is lower than an uphill wheel and the frame assembly has at least a predetermined lateral tilt. The controller is operable to process the lateral tilt signal and responsively control the respective amounts of power from the engine assembly to one or more of the vertical movers to move the frame assembly from the lateral tilted condition into a generally horizontally level condition. Each of the vertical movers is provided with a separate manually actuatable second vertical mover in series therewith and a manually actuated lateral tilt system is operatively connected to each second vertical mover to cause power from the engine assembly to move the second vertical mover in accordance with a selected manual actuation thereof. The controller is rendered operable when processing a turning signal as aforesaid to responsively provide a greater amount of power from the engine assembly to an outer vertical mover with respect to the angle of turn than to an inner vertical mover with respect to the angle of turn so that the faster rotating outer wheel is provided with greater ground pressure and increased traction and any lateral tilt of the frame assembly during the turn is stabilized.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.